11gR2 database installation comes up with new  feature known as Installation Fixup scripts which aids you during Installation phase.  If a pre-requisite check fails, then it provides a click and generate fixup script option and then points you to script location which then need’s to be executed  with root permission. As per doc’s , it takes care of following things

– Checks and sets kernel parameters to values required for successful installation, including:Shared memory parameters,Semaphore parameters and Open file descriptor and UDP send/receive parameters

– Sets permissions on the Oracle Inventory directory.

– Reconfigures primary and secondary group memberships for the installation owner, if necessary, for the Oracle Inventory directory, and for the operating system privileges groups.

– Sets up virtual IP and private IP addresses in /etc/hosts.

– Sets shell limits to required values, if necessary.

– Installs the Cluster Verification Utility packages (cvuqdisk rpm).

Below are screenshot for error’s encountered as a result of missing kernel settings in sysctl.conf file

Below is output of running the script as root

cat orarun.log
This is the log file for orarun script
Timestamp: 090109150435
Response file being used is :/tmp/CVU_11.2.0.1.0_oracle/fixup.response
Enable file being used is :/tmp/CVU_11.2.0.1.0_oracle/fixup.enable
Setting Kernel Parameters...
file-max in response file:6815744
file-max in /etc/sysctl.conf:6815744
The value for file-max in response file is not greater than value for file-max in /etc/sysctl.conf file. Hence not changing it.
file-max for current session:6553600
ip_local_port_range in response file:9000 65500
ip_local_port_range in /etc/sysctl.conf:9000 65000
ip_local_port_range for current session:1024 65000
aio-max-nr in response file:1048576
aio-max-nr in /etc/sysctl.conf:1048576
The value for aio-max-nr in response file is not greater than value for aio-max-nr in /etc/sysctl.conf file. Hence not changing it.
aio-max-nr for current session:65536

Before running the script, I had modified the file without executing sysctl -p to implement the changes.  Fixup script log  shows that it checks the file again and replaces parameter if required and then executes sysctl command to  make changes persistent.